Bad comes in all directions in "Be Kind Rewind." There are crosscurrents of bad, scenes that fail in two or three ways simultaneously, as farce, as sentiment and as storytelling. The energy of Jack Black's attack and Mos Def's talent for moment-by-moment honest thinking onscreen can't disguise it. The presence of Danny Glover can't class things up. Inside 10 minutes, at most 15, "Be Kind Rewind" reveals itself as an awful mess, and it only gets worse.

It's set mainly in a video store of a type that hardly exists anymore, a single proprietorship offering only dusty VHS tapes and titles from years ago. Mos Def plays a guy who works there, and Black is his crazy, zany friend who - under circumstances not worth going into, but the movie gets into them - gets himself magnetized and accidentally erases every movie in the store. And so the two buddies set out to remake the movies themselves, starring themselves.

This is a delicate comic idea, in that it's wildly unrealistic but it has good farcical potential. The guys would have to be really stupid to believe they could fool people, and the people would have to be really stupid in order to be fooled, but in a wacked-out comic universe, such a concept could fly. Its chief virtue would be the opportunity for Black and Mos Def to parody an unlimited number of well-known movies. Sounds fun (maybe).

The first surprise is that it's not fun at all. The two friends' initial foray is to re-create "Ghostbusters," and there isn't a laugh in the whole sequence. It's just witless and charmless. The second surprise is that "Be Kind Rewind" doesn't take place in some hyper-comic dimension. It stays grounded in what it wants to pass off as reality, with a saccharine plot strain involving the city's attempt to close down and demolish the video store for safety violations.

The realistic convention undermines the comedy and puts a burden on the story, which is forced to make at least some kind of sense. In a farce, it would be perfectly acceptable, for example, to have scores of customers who actually prefer the remakes. That could be funny. But in story about a downtrodden business owner (Glover) trying to keep his humble enterprise alive, such a turn seems merely sentimental and fake.

So we have fake. We have sentimental. And then we have yet more scenes of Black and Mos Def remaking popular films, but they're still not able to buy a laugh. Considering that the comic appeal and the entire story of "Be Kind Rewind" turns on the quality and fun factor of these scenes, one would expect writer-director Michel Gondry to have found a way to give his characters some kind of accidental talent or quirky appeal. If this comedy had nothing else, the scenes of the guys filming their remakes should have been surefire. But all we get is the spectacle of Black and Mos Def flailing as they play two idiots who are flailing. If we don't want to watch them, why would customers pay for home videos as bad they could make themselves?

Into this already thick stew of awful, Gondry adds an incongruous element: a Fats Waller connection. Everybody in the movie is a Fats Waller fan. Everybody in the movie was just talking about him yesterday. The nostalgia lends a further note of sentiment to this farcical construct, and it helps like a tractor on a front lawn.